Tissue and towel products such as facial tissues, paper towels, bath tissues, napkins and other similar products, are designed to include several important properties. For example products should have good bulk, good absorbency, a soft feel, and should have good strength and durability. Unfortunately, when steps are taken to increase one property of the product, other characteristics of the product are often adversely affected.
Formulators have for years attempted to balance a higher level of softwood fibers in their paper structures to ensure adequate strength of their structures while at the same time trying to minimize the negative impact on softness, durability or absorbency generally resulting from higher levels of softwood fibers. One example of the problem has been that formulators of bath tissue products have been unable to reliably make acceptable fibrous structures, for example multi-density structures made by through-air-dried (“TAD”) processes, that contain less than 20% by weight softwood fibers on a dry fiber basis without requiring excessive refining of the softwood fibers and/or adding excessive chemical strength agents to achieve the desired level of strength and/or reliability (avoid sheet breaks during making and/or processing).
Similarly, for paper toweling products, formulators work to develop new products that have higher in-use strength at lower or equal dry strength. However, as formulators use typical paper making process variables to increase product in-use or wet strength, other consumer desired attributes such as absorbency and/or softness typically decrease. The typical problem formulators struggle with for paper toweling is how to increase towel in use or wet strength while maintaining or improving softness and/or absorbency, or how to decrease softwood inclusion while maintaining total product strength and/or sheet flexibility. All of the normal paper making process variables available to a papermaker for increasing strength, normally can negatively affect the sheet feel and product absorbency.
Accordingly there continues to be a need for new fibrous papers structure that further optimize the physical product performance of tissue and towel products that increase wet and dry strength without sacrificing as much softness, absorbency and paper making reliability. Such structures are especially valuable for multi-density paper making structures with non-limiting examples of such structures being through air dried, Fabric Crepe. NTT, ATMOS and UCTAD processes.